The rainbow pinwheel teaches your students an important characteristic of light: rainbow colors, blended together, actually blend into white light. Use a cardboard circle, sheets of paper colored red, orange, yellow, green, blue, indigo, violet, a wood dowel, and a thumbtack. Cut the seven sheets into wedges and glue them so that they form a rainbow pinwheel around the cardboard circle. Put a thumbtack in the middle of the cardboard circle and pin it to the dowel. Take it outside in bright light and spin it. The faster you spin it, the whiter it appears. Explain to your student that white light is actually made up of the colors of the rainbow.
Harness solar energy to etch cool designs into wood. Warning: do this outside, supervise your students at all times, and have a bucket of water and/or hose at the ready. You need a magnifying glass, a pencil, and some wood.
Have your student draw a pattern, using the pencil, on the wood. Use the magnifying glass to focus sunlight onto a tiny spot of the wood, causing the wood to char. Move the magnifying glass along the wood, creating a decorative pattern built into the wood. Get your students excited about the power of the sun!
Harness solar power to purify water. You need a large clear bowl, cling wrap, a clean drinking glass, salt, food dye, ordinary drinking water, and a pebble. Mix up the ordinary drinking water in the bowl, with all sorts of spices to make it nasty -- such as curry powder, cinnamon, ginger, etc. Place the empty water drinking glass in the center of the bowl, cover with cling wrap, place a pebble over the center of the water drinking glass on top of the cling wrap. Place in the sunshine.
The plastic wrap will trap heat from the sun, and the water will absorb it. The water will evaporate, forming water vapor that condenses on the plastic wrap and drips down the underside of the plastic wrap to the point where the pebble is sitting, and drips into the cup. Ta-da! The water should be fine to drink.
Measure the difference between dark and light can's rates of heat absorption. You need two aluminum cola cans, black and white paint, a thermometer, and water. To make graphs, you'll also need Microsoft Excel or an equivalent graphing program.
Fill the cans halfway with tap water. Paint one white and one black. Place a thermometer in each can. Place cans in the sunlight. After a minute, read and record the temperature of water in both cans. Repeat every thirty seconds.
This experiment shows your students that darker materials absorb sunlight energy more quickly than lighter materials. This finding can segue into a discussion of the different characteristics that make solar panels more or less effective at absorbing solar energy.